PLANT OF THE WEEK: African blue basil / There's a new basil on the (foggy San Francisco) block

Published 4:00 am, Saturday, July 23, 2005

PLANT OF THE WEEK: African blue basil / There's a new basil on the (foggy San Francisco) block

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Last summer my Italian American neighbors grew some basil in a fish tank. No, they didn't think it was an aquatic plant; they were suffering from fresh basil deficiency and hoped the glass would concentrate enough heat to let the basil grow in our foggy San Francisco neighborhood. Grow it did, if a bit elongated and twisted, and produced enough leaves to snip now and then for seasoning.

I share my neighbors' frustration with basil's pouting refusal to grow in our cool summer weather. And I know others share our frustration, because when I tell my students at City College that basil doesn't grow well in foggier neighborhoods, I always hear a group sigh of disappointment. Therefore, I was delighted when I learned of a basil that grows into a reasonably large plant in the fog, and into an extra big and bushy one in slightly sunnier gardens. I was even more delighted when I was offered some for use in my kitchen and found that it made great pesto -- and that I can buy it in local nurseries. It's this year's garden sensation on our foggy San Francisco block!

Description: The variety is African blue basil. It is a decorative plant, which, if allowed to bloom, is covered with long flower stems of purple buds that open to lavender flowers. The 1- to 2 1/2-inch long leaves are a slightly grayed green with purple speckles on their undersides. The plant grows 1 1/2 to 2 feet tall when pinched to harvest, but would grow taller unpinched, and is much bushier than regular basil varieties.

African blue basil (Ocimum kilimandscharicum x basilicum 'Dark Opal') is an accidental hybrid between an East African basil and a garden variety basil called 'Dark Opal.' The African parent is a perennial shrub from forests of Kenya, Tanzania and Uganda, valued for its camphor scent.

African blue basil was first seen in 1983 when Peter Borchard, owner of Companion Plants in Athens, Ohio, noticed it growing in the path between beds of the two presumed parents. The green-leaved East African basil parent grows to 6 feet tall in his garden. 'Dark Opal' is a small plant with deep purple leaves and a typical Italian basil flavor. Borchard dug the hybrid and brought it into the greenhouse, hoping to save seed, but the cross between the two species seems to be too far a stretch, because no seed formed. Borchard grew more plants from cuttings, and by cuttings has African blue basil entered the herb market.

Cultivation: Plant African blue basil in spring to midsummer in a sunny spot that is as protected as possible from cold winds. Be sure it has well- amended, fertile soil and that you can keep the soil moist. It will do well in a container, but to avoid stunting the plant, use one that is 10 to 12 inches across the top.

Pinching off the tips of basil stems makes the plant have more branches. When you get your young plant, you should at first pinch out its center stem. If it is very small, wait until the plant has at least 4 pairs of leaves, and pinch off the top set. Or, if the plant is already blooming, pinch out the center flower head and a couple of leaves beneath it as well as any side flower heads more than an inch long. If you plan to grow the plant as an ornamental, pinch new stem tips once or twice more as they grow, then let the plant bloom.

The plants are tender perennials that will decline in winter and be killed by frost. If you want to try to root cuttings to overwinter indoors, you will have the best luck if you start them by midsummer, while the plant is still vigorous and the sun is still strong. My inclination is to buy new plants each spring, since my efforts to overwinter cuttings last year didn't produce vigorous plants. This may have been because I rooted them too late in the summer, but also they were weakened by the herds of aphids that attack any basil I grow indoors.

I have had no aphid attacks outdoors. Snails did nibble a bit, but the plant seems much less attractive to them than regular basil, and its quick growth rate also helps it escape serious damage.

Harvest: You can start by eating the first pinchings, then continue to pinch off tips that include several sets of leaves as the plant continues to grow, never taking more than half of the plant at a time. Preventing blooms will help put more of the plant's energy into making leaves, but you can let the flower heads get several inches long and still eat them.

Preparation: The flowers, leaves and young stems are edible. Some sources report that the flavor is too camphory, but everyone who has tried mine so far thinks it has a rich, mellow flavor. Finely chopped basil is a classic ingredient of pesto sauce and is delicious seasoning for soups, salads and dishes containing tomato, summer or winter squash, green beans, chicken, fish or red meats.

For a tasty salad, arrange thin slices of summer ripe tomato and cucumber or raw zucchini on small individual plates. Sprinkle each plate with 1 1/2 teaspoons of dry roasted pine nuts and a teaspoon or so of African blue basil flowers or chopped leaves. Dress with a vinaigrette made by shaking together in a jar 3 parts olive oil, one part balsamic vinegar, salt, pepper and garlic powder to taste. (Dry roast the pine nuts by heating a small skillet until it is very hot, then adding the pine nuts and tossing until they are just beginning to brown. Turn off the heat and turn the pine nuts into a bowl to cool.)

I make pesto using the recipe in my "Golden Gate Gardening" book: Put in the bowl of a blender or food processor: 1/4 cup olive oil, 1/3 cup water, 1/4 cup raw, unsalted almonds or pine nuts, 2 cloves of garlic, chopped coarsely, and 2 cups of basil leaves, stems and flowers, chopped coarsely and packed lightly into the measure. Blend well, stirring unblended bits back into the mixture and reblending as needed. Transfer the mixture into a bowl and stir in 3/4 cup of grated Parmesan cheese. Boil pasta, and when it's cooked, spoon a bit of boiling water from its pot into the pesto. Stir the water in and add a bit more until the pesto is the consistency you want. Serve over the drained pasta. Serves 2 or 3.

Availability

African blue basil plants from the wholesale nursery Sweetwater-Organics are available in many Bay Area nurseries.